Calcium chloride, a classical concrete-set accelerator, promotes (in the concrete) a continuous oxidation of ferrous structural or reinforcing steel or aluminum (conduits) embedded therein. It also adversely influences the concrete itself in the form of resulting cracking, spalling and weakening; it increases the attack of sulfates in soil. Generally, the maximum amount of calcium chloride used per bag (94 pounds) of cement is two pounds.
Naphthalene sulfonic acid condensates (with iso-propyl or iso-butyl alcohol) were suggested by Nelson [U.S. Pat. No. 1,863,990] as additives to wall plasters and mortars to reduce surface tension, improve wetting, increase plasticity and improve working.
Tucker [U.S. Pat. Nos. 1,972,207, 1,972,208 and 2,141,569] disclosed (naphthalene sulfonic acid)/formaldehyde condensates to enhance the hue of colored calcareous substances; the last-cited patent expanded the condensate to include those wherein the naphthalene sulfonic acid is replaced by other aromatic sulfonic acids, such as those of benzene, of diphenyl, of phenanthrene and of anthracene, and the resulting concrete or cement additive was suggested to reduce the amount of required water and to increase the strength of hardened concrete. Tucker provided a synthesis for his condensates which were later [U.S. Pat. No. 2,690,975] recognized as "Tucker's condensation product" or "Tucker C-P."
In connection with maintaining a stable suspension or assisting flow of a cement slurry, Wertz [U.S. Pat. No. 2,313,107] warned that any condensate of formaldehyde with a polynuclear aromatic sulfonic acid should be used in very small quantities. MacPherson [U.S. Pat. No. 2,478,831] acknowledged the condensation product of naphthalene sulfonic acid and formaldehyde as a cement dispersing agent. Scripture [U.S. Pat. No. 2,690,975] reported that Tucker's condensation product and its many variants do reduce the amount of water required to produce a cement mix having a given plasticity, but do not materially increase the ultimate strength of the hardened cement mix; they have little or no effect on early strengths at from 1 to 3 days. Scripture also stated that Tucker's condensation product and its variants have met with substantially no commercial success and proposed a comnination of such condensation product (cf. column 5, last complete paragraph) with desugarized waste sulfite liquor solids to reduce finishing time and improve early rate of gain of strength.
Benedict [U.S. Pat. No. 2,927,033] proposed Tucker's condensation product as one ingredient in a four-component cement additive, which also includes solids of waste sulfite liquor, water-soluble chloride accelerators and water-soluble alkyl amines.
Weisend [U.S. Pat. No. 3,132,693] proposed a mixture [40 to 50 percent by weight of hydroxyethyl cellulose, 2 to 10 percent by weight of 40,000 molecular weight polyvinylpyrrolidone (PVP), and 35 to 58 percent by weight of a sodium salt of a naphthalene sulfonate condensed with formaldehyde for which may be substituted any organic sulfonate dispersing agent] which provides a low-water-loss additive for cements. Weisend [U.S. Pat. No. 3,359,225] is directed to another additive [PVP (having an average molecular weight of the order of magnitude of 40,000) combined with the sodium salt of naphthalene sulfonate condensed with formaldehyde and having an average molecular weight of at least 1,500] for Portland-type cements "which reduces the friction encountered as the cement mixture is flowed or pumped into place, and which also permits the utilization of decreased quantities of water in the cement mixture, thus appreciably increasing the strength of the hardened and cured cement."
Hook [U.S. Pat. No. 3,465,825] found that the lithium (or the mixed lithiumsodium) salt of the condensation product (having a molecular weight of between about 500 and 3000) of mononaphthalene sulfonic acid and formaldehyde is a turbulence-inducing agent in aqueous cement slurries containing same. Proell [U.S. Pat. No. 3,537,869] concerns a 3-component [(a) partial fatty acid ester, (b) sulfate of a partial fatty acid ester or partial fatty alcohol ether, and (c) sulfonated condensation product of formaldehyde and a naphthalene or a salt thereof] additive for cementitious mixtures to increase the compressive strength of the hardened product. "Lomar D" ("a condensate of naphthalenesulfonic acids and formaldehyde, offered by the Nopco Chemical Company, Newark, N.J.") is so defined by Proell and is indicated by Ames [U.S. Pat. No. 3,582,376] to be a dispersant in quick-setting cement slurries.
Nishi [U.S. Pat. No. 3,677,780] produces high-strength mortar or concrete by subjecting shaped articles of mortar or concrete [containing a salt of .beta.-naphthalenesulfonic acid-formaldehyde condensate with at least two, and preferably at least five, .beta.-naphthalenesulfonic acid (.beta.-NS) units] to curing in an autoclave. Hattori [U.S. Pat. No. 3,686,133] found that a mixture of (a) a salt of a high molecular condensation product of naphthalene-(.alpha.- and .beta.-)sulfonic acid and formaldehyde and (b) a salt of gluconic acid is useful as a cement dispersing agent.
Kitsuda [U.S. Pat. No. 3,788,868] concerns water-soluble salts of condensates (having molecular weights of 1500 to 10,000) obtained by condensing with formaldehyde, sulfonated products of monocyclic or fused polycyclic benzenoid aromatic hydrocarbon compounds having from 1 to 12 benzene rings as cement dispersing agents.
The preceding is not intended to be a comprehensive review of disclosures concerning the use of naphthalenesulfonate/formaldehyde condensates in cement-containing compositions; it is merely indicative of the type of prior art presently known to Applicants.
Sodium nitrate has been suggested [U.S. Pat. No. 2,390,138] as an accelerator, and water-soluble sulfonated-aromatic-hydrocarbon/formaldehyde condensates have been employed as concrete additives [U.S. Pat. No. 1,972,207 and 1,972,208] for over forty years. These two materials, however, are not known to have been previously combined into a single composition for any purpose.